Ski



May 30, 1967 H. w. KIRSCHNER SKI Filed Jan. 29, 1965 HOWARD WILLIAMKIRSOHNER INVENTOR.

4 T TOR/V1575 United States Patent Filed Jan. 29, 1965, Ser. No. 428,96815 Claims. (Cl. 280-11.13)

The present invention relates to snow skis of the type in whichfiber-reinforced plastic is used as a structural material and in-closesa void or low density c-ore extending along a major part of the lengthof the ski.

While skis of this type have numerous advantages there have been certainattendant disadvantages, as for example, susceptibility of the upperedges of the ski to becoming badly worn or punctured by the runningedges of the skis if the skis are crossed during use. The presentinvention aims to provide protection for the upper edges of the skiswithout at the same time causing changes in the camber of the skis undervarious temperature conditions otherwise detracting from the performancelevel of the skis. The invention also aims to carry out this objectivewithout complicating the manufacturing procedure and unduly raisingproduction costs.

Another object of the invention is to provide an improved protectiverunning edge arrangement for skis which does not have any tendency totear loose from the body of the ski, particularly at the tip, underadverse skiing conditions.

Another object of the invention is to provide a ski having an unusuallyhigh strength to weight ratio and superior compressive strengths withoutchange of camber responsive to temperature change.

Another object is to provide a ski having a dampening effect allowing asoft tip but which still retains good holding characteristics on ice.

The invention further aims to provide such a ski which will have goodscrew-holding power for retaining bindings, particularly of theswivel-heel type.

Other more particular objects and advantages of the invention will, withthe foregoing, appear and be understood in the course of the followingdescription and claims, the invention consisting in the novelconstruction and in the adaptation and combination of parts hereinafterdescribed and claimed.

In the accompanying drawings:

FIG. 1 is a longitudinal vertical sectional view of a ski embodying thepresent invention;

FIG. 2 is an enlarged transverse vertical section taken on the line 2-2of FIG. 1;

FIG. 3 is a transverse cross-sectional view of a sub-unit of the skibefore the final assembly thereof;

FIG. 4 is a fragmentary detail bottom plan view of the ski with partsbroken away, and showing in phantom the forming at the tip of theforward running-edge strips;

FIG. 5 is a transverse cross-sectional diagrammatic view of the fiberlayer in the envelope which surrounds the core;

FIG. 6 is a detail fragmentary longitudinal vertical sectional viewtaken along the line 66 of FIG. 4; and

FIG. 7 is a transverse sectional view of a mold for forming the ski.

Referring to the accompanying drawings, it is seen that an improved ski10 constructed according to the present invention does not depart insize or shape from a conventional ski. In production the length, width,thickness and camber may be varied according to skier preference andrequirements and do not constitute part of the invention. Sheet metalscrews or other suitable fasteners may be used to mount the choice ofbindings (not shown) for boot retention.

As is conventional, the thickness of the ski varies along its length,being greatest at the center where the bending moments are normally themaximum when the ski is in use. Also, the ski is given a longitudinalcamber along the major part of its length and tilts up slightly at therear and more predominately at the front whereat the ski also tapersinwardly to a tip. The thickness of the ski along any given transversecross-section is shown substantially constant, but this is not essentialto the practice of the teachings of the invention.

In general, the ski 10 comprises a core 11 enclosed by afiber-reinforced synthetic resin envelope 12 to which are secured topedge protective strips 13, running edge protective strips 14a14b, andcompensating strips 15. There is also provided a bottom running layer 16and a top decorative layer 17. The core 11 is basically a filler and maybe formed of wood, such as spruce, or some other low density materialpreferably, although not essentially, having relatively good shearstrength. It is given a camber and thickness taper substantially inconformance with the finished ski through the central portion of itslength and is feathered at its ends. While the core 11 is illustrated asbeing formed from a single piece of wood, in which case it is preferredto have the wood grain extend longitudinally of the core, it is to beunderstood that it may be a laminated, cellular or hollow structure. Itis preferred that the core, either in its natural state or by theprovision of a coating, not absorb to any appreciable extent the resinused in the envelope.

As shown in FIG. 5, fibers for the envelope 12 may be arranged in threelayers. The two outer layers each comprise juxtaposed continuous fiberstrands extending the full length of the ski, the strands beinginitially held in their juxtaposed relation in any suitable manner suchas by transverse bands of plastic. Since the primary purpose of themiddle layer is to provide transversely or diagonally extending fibersthis can be accomplished by providing a woven fiber mat. Glass fibersare preferred for all of the layers, but it is to be understood thatother high-strength fiber may be suitable. It is also to be understoodthat the described fiber layers can be varied in arrangement or numbers,the primary purpose being to provide a substantial number of full lengthfibers so as to impart the desired bending strength to the ski and toalso have some of the fibers extending crosswise of the ski to resisttorsional deflection, particularly near the ends of the ski. Thus, thefibers may be provided in the form of yarn, cloth, mat, threads or cordto give the desired results.

It is preferred to provide the upper part of the envelope with thegreater strength. This is accomplished by first superimposing the fiberlayers upon one another in flat relation to form a laminated flat sheet,and then, after saturating the sheet with the resin and laying thereonthe core, botom face downward, wrapping first one side and then theother side of the sheet around the core so that the two longitudinaledge portions of the resulting envelope are in overlapping relation asshown in FIG. 5, thereby giving the top of the ski above the core adouble thickness of fibers relative to the portion of the envelopebeneath the core. The envelope is made the length of the desired ski(longer than the core) and is cut to a taper at the front in the generalmanner of the tip of the finished ski. A suitable thermosetting resinsuch as an epoxy characterized by good adhesiveness and flexibility isused for the envelope.

The running edge strips may be formed of tempered high carbon steel orsome other suitable hard non-brittle material and are of a generalL-shape in transverse crosssection so as to cover over the outer edgesof the running layer. Instead of providing a respective running edge foreach side of the ski as has been conventional in the ski art, I providea front strip 14a and a pair of back strips 14b?14b which meetapproximately half way '3 along the length of the ski at a pair of scarfjoints 22. As indicated in phantom in FIG. 4, the front running strip14a has its inner leg 14a formed with a generally V-shaped cutout 24midway the length of the strip so that the strip may be bent at the apexof the V to conform with the lateral taper at the tip of the ski. Thecurvature at the rear of the ski is gradual enough to permit the rearedge strip 14b to be die-formed in correspondence therewith.

The protective strips 13 and the compensating strips 15 are preferablyof like material, and may be of a tempered aluminum alloy, or of thesame material as the running-edge strips. Although the compensatingmembers 15 are shown in strip form they can be in rod form as well.

Also provided on the ski of the present invention, at the proximate bootheel position, is an aluminum mounting plate 23 which extends laterallybetween the upper protective strips 13 and is seated in a transverserecess 23a in the top of the core 11. This mounting plate has superiorholding power for holding sheet metal screws to the plastic envelope 12.

FIG. 7 illustrates the use of a mold suitable for constructing theimproved ski. The mold is inclusive of a female member having its cavitydimensioned and contoured to conform to the upper surface and edgeformation of the finished ski. The mouth of the mold 20 is formed with asmall peripheral step 20a to provide a relief point for the outer edgeof the running edge strips 14. The male die member 21 is shaped toconform to the lower surface of the finished ski as defined by the outeredges of the strips 14 and has a central ridge 21a through the majorpart of its length to provide the conventional center running groove.

The running layer 16 can be formed from a sheet of polyethylene or someother suitable material preferably of low moisture absorption and withlow coefficient of friction, which is tough and highly abrasionresistant. As indicated in FIG. 3, preparatory to the molding operationthe running-edge strips 14a14b and the tension strips 15 are bonded by asuitable adhesive to the upper face of the running layer to form acomposite sub-unit. This sub-unit is placed in the top of the mold 20 ininverted position after the mold has been charged with the protectivestrips 13 along its lower corners and the envelopecovered core ininverted position. The resin is preferably applied to the fiberlaminations of the envelope 12 before the core is wrapped therein. Afterthe mold is fully charged the male die 21 is pressed therein under about100 p.s.i. pressure and the mold heated to about 160 F. After partialcooling the ski is discharged, stress-relieved, and cured. Then thedecorative top layer 17 is bonded in position by a suitable adhesive.

The finished ski maintains a substantially constant camber under varyingtemperature conditions because stresses created by thermally-inducedchanges in length in the upper protective strips 13 are compensated forby like effects on the strips 15. In addition to its protectionfunction, the strip 13 is also valuable in contributing compressivestrength to the ski, particularly in the tip portion forward of the core11, without detracting from the performance level. The novel arrangementof the continuous running-edge strips 14a-14b securely holds them inplace even under extremely adverse skiing conditions, and helps toresist warping.

It is believed that the invention will have been clearly understood fromthe foregoing detailed description of my now-preferred illustratedembodiment. Changes in the details of construction may be resorted towithout departing from the spirit of the invention and it is accordinglymy intention that no limitations be implied and the hereto annexedclaims be given the broadest interpretation to which the employedlanguage fairly admits.

What I claim is:

1. A ski comprising, an elongated core of low density material, top andbottom layers of high density, resinous,

fibrous material bonded to the upper and lower faces of said core,protective strips secured along the upper longutudinal edges of said toplayer, running-edge strips secured along the bottom longitudinal edgesof said bottom layer, and compensating means secured to said bottomlayer and extending longitudinally thereof for balancing stressescreated by temperature changes in said upper protective strips.

2. A ski according to claim 1 in which said upper protective strips andsaid compensating means are formed of the same material.

3. A ski according to claim 1 in which said upper protective strips areformed of tempered aluminum, and in which said compensating meanscomprises a pair of tempered aluminum strips.

4. A ski according to claim 1 in which said core comprises a wood piecefeathered at its ends and with its grain extending longitudinally of thecore.

5. A ski according to claim 1 in which said top and bottom layers areprovided by an envolope which encloses said core and extends well beyondat least one end of the core to form the tip portion of the ski.

6. A ski according to claim 5 in which said protective strips andcompensating means are bonded to said envelope.

7. A ski according to claim 1 in which said compensating means comprisesa pair of longitudinal strips of the same material as said upperprotective strips and located between said running edge strips.

8. A ski according to claim 1 in which a running layer is bonded to saidbottom layer, compensating means, and running-edge strips for providingthe bottom running surface of the ski.

9. A ski according to claim 8 in which a decorative layer is bonded tothe top of said top layer and protective strips.

10. A ski according to claim 1 in which said top layer includes aplurality of continuous glass fibers.

11. A ski according to claim 1 in which said runningedge strips comprisea front continuous strip having its two ends at the central part of theski and extending continuously therefrom around the tip of the ski, andback strips continuingrearwardly from said two ends of the front strip.

12. A ski according to claim 11 in which the front and back strips meetat a pair of beveled butt joints in which the front strip overlaps theback strips.

13. A ski according to claim 1 in which said top and bottom layers areformed by a resin-impregnated laminated fiber sheet which encloses saidcore and has its longitudinal side edge portions overlapped on the topof the core.

14. A ski according to claim 13 in which a majority of the laminacomprise continuous glass fibers extending the length of the sheet.

15. A ski according to claim 1 in which a mounting plate for skibindings is secured to said core.

References Cited UNITED STATES PATENTS 1,993,636 3/1935 Ullevoldsaeter28011.13 2,225,293 12/1940 Bjork 280-1 1.13 2,695,178 11/1954 Rheinfrank280-11.13 3,199,882 8/1965 Peillex 280-1 1.13

FOREIGN PATENTS 572,337 3/1959 Canada.

927,897 5/ 1947 France. 1,234,047 5/ 1960 France. 1,261,653 4/1961France. 1,380,102 10/ 1964 France.

BENJAMIN HERSH, Primary Examiner.

MILTON L. SMITH, Examiner.

1. A SKI COMPRISING AN ELONGATED CORE OF LOW DENSITY MATERIAL, TOP AND BOTTOM LAYERS OF HIGH DENSITY, RESINOUS, FIBROUS MATERIAL BONDED TO THE UPPER AND LOWER FACE OF SAID CORE, PROTECTIVE STRIPS SECURED ALONG THE UPPER LONGITUDINAL EDGES OF SAID TOP LAYER, RUNNING-EDGE STRIPS SECURED ALONG THE BOTTOM LONGITUDINAL EDGES OF SAID BOTTOM LAYER, AND COMPENSATING MEANS SECURED TO SAID BOTTOM LAYER AND EXTENDING LONGITUDINALLY THEREOF FOR BALANCING STRESSES CREATED BY TEMPERATURE CHANGES IN SAID UPPER PROTECTIVE STRIPS. 